Reverse link feedback for interference control in a wireless communication system

ABSTRACT

Systems and methodologies are described that provide techniques for generating and utilizing reverse link feedback for interference management in a wireless communication system. Channel quality and/or interference data can be obtained by a terminal from a serving sector and one or more neighboring sectors, from which an interference-based headroom value can be computed that contains interference caused by the terminal to an allowable range. The interference-based headroom value can then be provided with power amplifier (PA) headroom feedback to the serving sector. Based on the provided feedback from the terminal, the serving sector can assign resources for use by the terminal in communication with the serving sector. Further, the serving sector may choose to honor or disregard a received interference-based power value based on quality of service and/or other system parameters.

CROSS-REFERENCE

This application is a Divisional of U.S. patent application Ser. No.11/848,755 entitled “REVERSE LINK FEEDBACK FOR INTERFERENCE CONTROL IN AWIRELESS COMMUNICATION SYSTEM,” filed Aug. 31, 2007, which claims thebenefit of U.S. Provisional Application Ser. No. 60/843,034, filed Sep.8, 2006, and entitled “REVERSE LINK FEEDBACK FOR INTERFERENCE CONTROL INA WIRELESS COMMUNICATION SYSTEM,” the entirety of which is incorporatedherein by reference.

BACKGROUND

I. Field

The present disclosure relates generally to wireless communications, andmore specifically to techniques for power and interference control in awireless communication system.

II. Background

Wireless communication systems are widely deployed to provide variouscommunication services; for instance, voice, video, packet data,broadcast, and messaging services may be provided via such wirelesscommunication systems. These systems may be multiple-access systems thatare capable of supporting communication for multiple terminals bysharing available system resources. Examples of such multiple-accesssystems include Code Division Multiple Access (CDMA) systems, TimeDivision Multiple Access (TDMA) systems, Frequency Division MultipleAccess (FDMA) systems, and Orthogonal Frequency Division Multiple Access(OFDMA) systems.

A wireless multiple-access communication system can simultaneouslysupport communication for multiple wireless terminals. In such a system,each terminal can communicate with one or more sectors via transmissionson the forward and reverse links. The forward link (or downlink) refersto the communication link from the sectors to the terminals, and thereverse link (or uplink) refers to the communication link from theterminals to the sectors.

Multiple terminals can simultaneously transmit on the reverse link bymultiplexing their transmissions to be orthogonal to one another in thetime, frequency, and/or code domain. If complete orthogonality betweentransmissions is achieved, transmissions from each terminal will notinterfere with transmissions from other terminals at a receiving sector.However, complete orthogonality among transmissions from differentterminals is often not realized due to channel conditions, receiverimperfections, and other factors. As a result, terminals often causesome amount of interference to other terminals communicating with thesame sector. Furthermore, because transmissions from terminalscommunicating with different sectors are typically not orthogonal to oneanother, each terminal may also cause interference to terminalscommunicating with nearby sectors. This interference results in adecrease in performance at each terminal in the system. Accordingly,there is a need in the art for effective techniques to mitigate theeffects of interference in a wireless communication system.

SUMMARY

The following presents a simplified summary of the disclosed embodimentsin order to provide a basic understanding of such embodiments. Thissummary is not an extensive overview of all contemplated embodiments,and is intended to neither identify key or critical elements nordelineate the scope of such embodiments. Its sole purpose is to presentsome concepts of the disclosed embodiments in a simplified form as aprelude to the more detailed description that is presented later.

The described embodiments mitigate the above-mentioned problems byproviding techniques for generating, communicating, and utilizingreverse link feedback for interference management in a wirelesscommunication system. More particularly, a terminal in a wirelesscommunication system can obtain channel quality and/or interference datafrom a serving sector and one or more neighboring sectors, from whichthe terminal can determine a maximum transmit power that containsinterference caused by the terminal to an allowable range. Thisinterference-based maximum transmit power can then be provided withpower amplifier (PA) headroom feedback to the serving sector. Based onthe provided PA headroom feedback and interference-based maximumtransmit power, the serving sector can then assign a transmit power forthe terminal Additionally and/or alternatively, the serving sector maychoose to honor or disregard a received interference-based power valuebased on quality of service and/or other system parameters.

According to an aspect, a method for providing feedback for powercontrol in a wireless communication system is described herein. Themethod can comprise determining a combined power amplifier (PA) headroomand interference value for communication with an access point. Inaddition, the method can include transmitting the combined value to theaccess point.

Another aspect relates to a wireless communications apparatus that cancomprise a memory that stores data relating to a difference in channelquality between a serving sector and a dominant interference sector anddata relating to a target interference level. The wirelesscommunications apparatus can also include a processor configured tocompute a combined PA headroom and interference value based at least inpart on the difference in channel quality and the target interferencelevel and to instruct transmission of the combined value to the servingsector.

Yet another aspect relates to an apparatus that facilitates reverse linkpower control and interference management in a wireless communicationsystem. The apparatus can include means for computing one or moreinterference-based headroom parameters for communication with a servingbase station. Further, the apparatus can include means for communicatingthe one or more interference-based headroom parameters to the servingbase station with PA headroom feedback.

Still another aspect relates to a computer-readable medium that cancomprise code for causing a computer to determine a PA headroomparameter and an interference-based headroom parameter. Thecomputer-readable medium can further include code for causing a computerto communicate the PA headroom parameter and the interference-basedheadroom parameter to an access point.

According to another aspect, an integrated circuit is described hereinthat can execute computer-executable instructions for interferencecontrol in a wireless communication system. These instructions caninclude obtaining a maximum per-user interference and a path loss to atleast one sector in the wireless communication system. The instructionscan further include computing a combined PA headroom and interferencevalue based at least in part on the maximum per-user interference andthe path loss. In addition, the instructions can comprise transmittingthe combined value to a serving sector.

According to yet another aspect, a method for conducting power controland interference management in a wireless communication system isdescribed herein. The method can comprise receiving a combined PAheadroom and interference value from an access terminal. The method canadditionally include assigning one or more of a transmit power and abandwidth for the access terminal based at least in part on the combinedvalue.

Another aspect described herein relates to a wireless communicationsapparatus that can include a memory that stores data relating to a PAheadroom parameter and an interference-based headroom parameter receivedfrom a terminal In addition, the wireless communications apparatus cancomprise a processor configured to assign a transmit power for theterminal based on at least one of the PA headroom parameter and theinterference-based headroom parameter.

Yet another aspect relates to an apparatus that facilitates reverse linkpower control and interference management in a wireless communicationsystem. The apparatus can comprise means for receiving PA headroomfeedback and interference-based headroom feedback from a mobile terminalFurther, the apparatus can comprise means for assigning resources to themobile terminal for communication based on one or more of the PAheadroom feedback and the interference-based headroom feedback.

Still another aspect relates to a computer-readable medium that cancomprise code for causing a computer to determine a transmit PSD to beutilized by an access terminal based at least in part on a combined PAheadroom and interference value received from the access terminal. Thecomputer-readable medium can further include code for causing a computerto communicate the transmit PSD to the access terminal

A further aspect described herein relates to an integrated circuit thatcan execute computer-executable instructions for power control andinterference management in a wireless communication system. Theseinstructions can comprise receiving a PA headroom value from a terminal,the PA headroom value limited by an interference value on a reverselink. The instructions can further comprise generating an assignment ofresources for use by the terminal based on the PA headroom value and theinterference value. In addition, the instructions can includecommunicating the assignment of resources to the terminal on a forwardlink.

To the accomplishment of the foregoing and related ends, one or moreembodiments comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative aspects ofthe disclosed embodiments. These aspects are indicative, however, of buta few of the various ways in which the principles of various embodimentsmay be employed. Further, the disclosed embodiments are intended toinclude all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless multiple-access communication system inaccordance with various aspects set forth herein.

FIG. 2 is a block diagram of a system that facilitates reverse linkpower control and interference management in a wireless communicationsystem in accordance with various aspects.

FIGS. 3A-3C illustrate operation of an example system for power controland interference management in a wireless communication system inaccordance with various aspects.

FIG. 4 is a flow diagram of a methodology for providing reverse linkfeedback for power control and interference management in a wirelesscommunication system.

FIG. 5 is a flow diagram of a methodology for conducting reverse linkpower control in a wireless communication system.

FIG. 6 is a flow diagram of a methodology for generating andtransmitting reverse link feedback for power control and interferencemanagement in a wireless communication system.

FIG. 7 is a flow diagram of a methodology for assigning a transmit powerto a terminal for reverse link power control and interference managementin a wireless communication system.

FIG. 8 is a block diagram illustrating an example wireless communicationsystem in which one or more embodiments described herein may function.

FIG. 9 is a block diagram of a system that provides reverse linkfeedback for interference control in a wireless communication system inaccordance with various aspects.

FIG. 10 is a block diagram of a system that coordinates reverse linkpower control and interference management in a wireless communicationsystem in accordance with various aspects.

FIG. 11 is a block diagram of an apparatus that facilitates reverse linkfeedback for interference management in a wireless communication system.

FIG. 12 is a block diagram of an apparatus that facilitates thegeneration and transmission of reverse link feedback for power controland interference management in a wireless communication system.

FIG. 13 is a block diagram of an apparatus that facilitates reverse linkpower control in a wireless communication system.

FIG. 14 is a block diagram of an apparatus that facilitates theprovision of a transmit power assignment to a terminal for reverse linkpower control and interference management in a wireless communicationsystem.

DETAILED DESCRIPTION

Various embodiments are now described with reference to the drawings,wherein like reference numerals are used to refer to like elementsthroughout. In the following description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of one or more aspects. It may be evident, however, thatsuch embodiment(s) may be practiced without these specific details. Inother instances, well-known structures and devices are shown in blockdiagram form in order to facilitate describing one or more embodiments.

As used in this application, the terms “component,” “module,” “system,”and the like are intended to refer to a computer-related entity, eitherhardware, firmware, a combination of hardware and software, software, orsoftware in execution. For example, a component may be, but is notlimited to being, a process running on a processor, a processor, anobject, an executable, a thread of execution, a program, and/or acomputer. By way of illustration, both an application running on acomputing device and the computing device can be a component. One ormore components can reside within a process and/or thread of executionand a component may be localized on one computer and/or distributedbetween two or more computers. In addition, these components can executefrom various computer readable media having various data structuresstored thereon. The components may communicate by way of local and/orremote processes such as in accordance with a signal having one or moredata packets (e.g., data from one component interacting with anothercomponent in a local system, distributed system, and/or across a networksuch as the Internet with other systems by way of the signal).

Furthermore, various embodiments are described herein in connection witha wireless terminal and/or a base station. A wireless terminal may referto a device providing voice and/or data connectivity to a user. Awireless terminal may be connected to a computing device such as alaptop computer or desktop computer, or it may be a self containeddevice such as a personal digital assistant (PDA). A wireless terminalcan also be called a system, a subscriber unit, a subscriber station,mobile station, mobile, remote station, access point, remote terminal,access terminal, user terminal, user agent, user device, or userequipment. A wireless terminal may be a subscriber station, wirelessdevice, cellular telephone, PCS telephone, cordless telephone, a SessionInitiation Protocol (SIP) phone, a wireless local loop (WLL) station, apersonal digital assistant (PDA), a handheld device having wirelessconnection capability, or other processing device connected to awireless modem. A base station (e.g., access point) may refer to adevice in an access network that communicates over the air-interface,through one or more sectors, with wireless terminals. The base stationmay act as a router between the wireless terminal and the rest of theaccess network, which may include an Internet Protocol (IP) network, byconverting received air-interface frames to IP packets. The base stationalso coordinates management of attributes for the air interface.

Moreover, various aspects or features described herein may beimplemented as a method, apparatus, or article of manufacture usingstandard programming and/or engineering techniques. The term “article ofmanufacture” as used herein is intended to encompass a computer programaccessible from any computer-readable device, carrier, or media. Forexample, computer readable media can include but are not limited tomagnetic storage devices (e.g., hard disk, floppy disk, magnetic strips. . . ), optical disks (e.g., compact disk (CD), digital versatile disk(DVD) . . . ), smart cards, and flash memory devices (e.g., card, stick,key drive . . . ).

Various embodiments will be presented in terms of systems that mayinclude a number of devices, components, modules, and the like. It is tobe understood and appreciated that the various systems may includeadditional devices, components, modules, etc. and/or may not include allof the devices, components, modules etc. discussed in connection withthe figures. A combination of these approaches may also be used.

Referring now to the drawings, FIG. 1 is an illustration of a wirelessmultiple-access communication system 100 in accordance with variousaspects. In one example, the wireless multiple-access communicationsystem 100 includes multiple base stations 110 and multiple terminals120. Further, one or more base stations 110 can communicate with one ormore terminals 120. By way of non-limiting example, a base station 110may be an access point, a Node B, and/or another appropriate networkentity. Each base station 110 provides communication coverage for aparticular geographic area 102. As used herein and generally in the art,the term “cell” can refer to a base station 110 and/or its coverage area102 depending on the context in which the term is used.

To improve system capacity, the coverage area 102 corresponding to abase station 110 may be partitioned into multiple smaller areas (e.g.,areas 104 a, 104 b, and 104 c). Each of the smaller areas 104 a, 104 b,and 104 c may be served by a respective base transceiver subsystem (BTS,not shown). As used herein and generally in the art, the term “sector”can refer to a BTS and/or its coverage area depending on the context inwhich the term is used. In one example, sectors 104 in a cell 102 can beformed by groups of antennas (not shown) at base station 110, where eachgroup of antennas is responsible for communication with terminals 120 ina portion of the cell 102. For example, a base station 110 serving cell102 a may have a first antenna group corresponding to sector 104 a, asecond antenna group corresponding to sector 104 b, and a third antennagroup corresponding to sector 104 c. However, it should be appreciatedthat the various aspects disclosed herein may be used in a system havingsectorized and/or unsectorized cells. Further, it should be appreciatedthat all suitable wireless communication networks having any number ofsectorized and/or unsectorized cells are intended to fall within thescope of the hereto appended claims. For simplicity, the term “basestation” as used herein may refer both to a station that serves a sectoras well as a station that serves a cell. As further used herein, a“serving” access point is one with which a given terminal communicates,and a “neighbor” access point is one with which a given terminal is notin communication. While the following description generally relates to asystem in which each terminal communicates with one serving access pointfor simplicity, it should be appreciated that terminals can communicatewith any number of serving access points.

In accordance with one aspect, terminals 120 may be dispersed throughoutthe system 100. Each terminal 120 may be stationary or mobile. By way ofnon-limiting example, a terminal 120 may be an access terminal (AT), amobile station, user equipment, a subscriber station, and/or anotherappropriate network entity. A terminal 120 may be a wireless device, acellular phone, a personal digital assistant (PDA), a wireless modem, ahandheld device, or another appropriate device. Further, a terminal 120may communicate with any number of base stations 110 or no base stations110 at any given moment.

In another example, the system 100 can utilize a centralizedarchitecture by employing a system controller 130 that can be coupled toone or more base stations 110 and provide coordination and control forthe base stations 110. In accordance with alternative aspects, systemcontroller 130 may be a single network entity or a collection of networkentities. Additionally, the system 100 may utilize a distributedarchitecture to allow the base stations 110 to communicate with eachother as needed. In one example, system controller 130 can additionallycontain one or more connections to multiple networks. These networks mayinclude the Internet, other packet based networks, and/or circuitswitched voice networks that may provide information to and/or fromterminals 120 in communication with one or more base stations 110 insystem 100. In another example, system controller 130 can include or becoupled with a scheduler (not shown) that can schedule transmissions toand/or from terminals 120. Alternatively, the scheduler may reside ineach individual cell 102, each sector 104, or a combination thereof.

In one example, system 100 may utilize one or more multiple-accessschemes, such as CDMA, TDMA, FDMA, OFDMA, Single-Carrier FDMA (SC-FDMA),and/or other suitable multiple-access schemes. TDMA utilizes timedivision multiplexing (TDM), wherein transmissions for differentterminals 120 are orthogonalized by transmitting in different timeintervals. FDMA utilizes frequency division multiplexing (FDM), whereintransmissions for different terminals 120 are orthogonalized bytransmitting in different frequency subcarriers. In one example, TDMAand FDMA systems can also use code division multiplexing (CDM), whereintransmissions for multiple terminals can be orthogonalized usingdifferent orthogonal codes (e.g., Walsh codes) even though they are sentin the same time interval or frequency sub-carrier. OFDMA utilizesOrthogonal Frequency Division Multiplexing (OFDM), and SC-FDMA utilizesSingle-Carrier Frequency Division Multiplexing (SC-FDM). OFDM and SC-FDMcan partition the system bandwidth into multiple orthogonal subcarriers(e.g., tones, bins, . . . ), each of which may be modulated with data.Typically, modulation symbols are sent in the frequency domain with OFDMand in the time domain with SC-FDM. Additionally and/or alternatively,the system bandwidth can be divided into one or more frequency carriers,each of which may contain one or more subcarriers. System 100 may alsoutilize a combination of multiple-access schemes, such as OFDMA andCDMA. While the power control techniques provided herein are generallydescribed for an OFDMA system, it should be appreciated that thetechniques described herein can similarly be applied to any wirelesscommunication system.

In another example, base stations 110 and terminals 120 in system 100can communicate data using one or more data channels and signaling usingone or more control channels. Data channels utilized by system 100 canbe assigned to active terminals 120 such that each data channel is usedby only one terminal at any given time. Alternatively, data channels canbe assigned to multiple terminals 120, which can be superimposed ororthogonally scheduled on a data channel. To conserve system resources,control channels utilized by system 100 can also be shared amongmultiple terminals 120 using, for example, code division multiplexing.In one example, data channels orthogonally multiplexed only in frequencyand time (e.g., data channels not multiplexed using CDM) can be lesssusceptible to loss in orthogonality due to channel conditions andreceiver imperfections than corresponding control channels.

In accordance with one aspect, system 100 can employ centralizedscheduling via one or more schedulers implemented at, for example,system controller 130 and/or each base station 110. In a systemutilizing centralized scheduling, scheduler(s) can rely on feedback fromterminals 120 to make appropriate scheduling decisions. In one example,this feedback can include power amplifier (PA) headroom feedback inorder to allow the scheduler to estimate a supportable reverse link peakrate for a terminal 120 from which such feedback is received and toallocate system bandwidth accordingly.

In accordance with another aspect, reverse link interference control canbe used by system 100 to guarantee minimum system stability and qualityof service (QoS) parameters for the system. For example, decoding errorprobability of reverse link (RL) acknowledgement messages can be used bysystem 100 as an error floor for all forward link transmissions. Byemploying tight interference control on the RL, system 100 canfacilitate power efficient transmission of control and QoS trafficand/or other traffic with stringent error requirements.

FIG. 2 is a block diagram of a system 200 that facilitates reverse linkpower control and interference management in a wireless communicationsystem in accordance with various aspects described herein. In oneexample, system 200 includes a terminal 210 ₁ that can communicate witha serving sector 220 on the forward and reverse links via one or moreantennas 216 ₁ at terminal 210 ₁ and one or more antennas 224 at servingsector 220. Serving sector 220 can be a base station (e.g., a basestation 110) or an antenna group at a base station. Further, servingsector 220 can provide coverage for a cell (e.g., a cell 102) or an areawithin a cell (e.g., a sector 104). In addition, system 200 can includeone or more neighbor sectors 230 that are not in communication withterminal 210 ₁. Neighbor sectors 230 can provide coverage for respectivegeographic areas that can include all, part, or none of an area coveredby serving sector 220 via one or more antennas 234. Further, system 200can include any number of additional terminals 210, which maycommunicate with serving sector 220 and/or one or more neighbor sectors230 via antennas 216.

In accordance with one aspect, a terminal 210 and a serving sector 220can communicate to control the amount of transmit power used by theterminal 210 in communicating with the serving sector 220 via one ormore power control techniques. In one example, a terminal 210 caninclude a headroom feedback component 212 that can report a total amountof transmit power available at the terminal to a serving sector 220.This report can be communicated to the serving sector as, for example,power amplifier (PA) headroom feedback and/or another suitable form offeedback from the terminal 210. By way of specific example, PA headroomfeedback provided by a terminal 210 can correspond to headroom withrespect to a pilot channel on which the terminal is transmitting, amaximum bandwidth supportable by the terminal at a nominal powerspectral density (PSD), and/or a maximum PSD achievable by the terminal

At the serving sector 220, a power control component 222 can thenutilize the PA headroom feedback and/or other feedback from a terminal210 to assign a transmit power to the terminal 210. In one example, PAheadroom feedback received at a serving sector 220 from a terminal 210can correspond to a maximum available transmit power at the terminal210. Accordingly, a power control component 222 at a serving sector 220can utilize PA headroom feedback from a terminal 210 to ensure that anassigned transmit power level does not exceed the maximum transmit powerindicated in the PA headroom feedback. After the power control component222 generates a transmit power assignment, the serving sector 220 cantransmit the assignment back to the terminal 210. The terminal 210 canthen accordingly adjust its transmit power based on the assignment via apower adjustment component 214.

In accordance with another aspect, power control techniques utilized byentities in system 200 can additionally take into account interferencepresent in system 200. For example, in a multiple access wirelesscommunication system such as an OFDMA system, multiple terminals 210 maysimultaneously conduct uplink transmission by multiplexing theirtransmissions to be orthogonal to one another in the time, frequency,and/or code domain. However, complete orthogonality betweentransmissions from different terminals 210 is often not achieved due tochannel conditions, receiver imperfections, and other factors. As aresult, terminals 210 in system 200 will often cause interference toother terminals 210 communicating with a common sector 220 or 230.Furthermore, because transmissions from terminals 210 communicating withdifferent sectors 220 and/or 230 are typically not orthogonal to oneanother, each terminal 210 may also cause interference to terminals 210communicating with nearby sectors 220 and/or 230. As a result, theperformance of terminals 210 in system 200 can be degraded by theinterference caused by other terminals 210 in system 200.

Accordingly, to provide the ability for a serving sector 220 toaccurately decode a transmission from a terminal 210 while maintainingan acceptable level of interference, entities in system 200 can performone or more interference-based power control algorithms. In one example,terminal 210 ₁ and serving sector 220 can communicate to carry out adelta-based power control algorithm. More particularly, a delta-basedpower control algorithm is designed for a channel, e.g., a data channel,where the delta refers to relative power spectral density (PSD), or asimilar metric, which is offset relative to a fixed channel such as achannel quality feedback or access/request channel. In another example,the fixed channel utilized in the delta-based power control algorithmcan have a minimum decode error rate target that must be met to ensureproper operation of system 200. The difference between the PSD of thechannel for which the delta-based power control algorithm is beingutilized and the fixed channel PSD can then be adjusted depending onerasure thresholds, carrier-to-interference ratios, interferenceoffsets, and/or other factors.

In accordance with another aspect, the amount of inter-cell interferencecaused by a given terminal 210 can be determined by the transmit powerlevel used by the terminal 210 and the location of the terminal 210relative to neighbor sectors 230. Based on this, power control can beperformed in system 200 such that each terminal 210 is allowed totransmit at a power level that is as high as possible while keepingintra-cell and inter-cell interference to within acceptable levels. Forexample, a terminal 210 located closer to its serving sector 220 may beallowed to transmit at a higher power level since the terminal willlikely cause less interference to neighbor sectors 230. Conversely, aterminal 210 located farther away from its serving sector 220 and towarda sector edge may be restricted to a lower transmit power level sincethe terminal may cause more interference to neighbor sectors 230. Bycontrolling transmit power in this manner, system 200 can reduce thetotal interference observed by sectors 220 and/or 230 while allowing“qualified” terminals 210 to achieve higher SNRs and thus higher datarates.

FIGS. 3A-3C are block diagrams that illustrate operation of an examplesystem 300 for power control and interference management in a wirelesscommunication system. In a similar manner to system 200, system 300 caninclude a terminal 310 in communication with a serving sector 320 on theforward and reverse links via respective antennas 316 and 324. System300 can also include one or more neighbor sectors (e.g., neighborsectors 330), which can include a dominant interference sector 330 thathas the most potential of being affected by interference caused byterminal 310 due to, for example, being the closest neighbor sector toterminal 310.

In accordance with one aspect, terminal 310 can communicate with servingsector 320 to control transmit power levels utilized by terminal 310. Inone example, power control techniques utilized by terminal 310 andserving sector 320 can be based on a level of interference caused byterminal 310 at serving sector 320 and/or other sectors such as dominantinterference sector 330. More particularly, terminal 310 can determinechannel quality parameters for serving sector 320 and/or dominantinterference sector 330, from which terminal 310 can compute aninterference value. The interference value can then be communicated toserving sector along with PA headroom feedback on the reverse link,based on which serving sector 320 can assign a transmit power level forterminal 310. By utilizing interference as a factor in power controltechniques employed by terminal 310 and serving sector 320, suchtechniques can facilitate more optimal overall performance in system 300than similar techniques that do not take interference into account.

In accordance with another aspect, interference-based power control canbe performed in system 300 using various techniques in order to increaseoverall performance of entities therein. In one such technique, transmitPower Spectral Density (PSD) for a data channel, or another suitablechannel having a power offset based upon another channel, can beexpressed for a given terminal 310 as follows:P _(dch)(n)=P _(ref)(n)+ΔP(n),  (1)where P_(dch) (n) is the transmit PSD for the data channel for an updateinterval n, P_(ref)(n) is a reference PSD level for update interval n,and ΔP(n) is a transmit PSD delta for update interval n. The PSD levelsP_(dch)(n) and P_(ref)(n) and the transmit power delta ΔP(n) can begiven in units of decibels (dB/Hz), although other units can beutilized. Further, it should be appreciated that calculations other thanthat given by Equation (1) can also be utilized. In one example, thereference PSD level P_(ref)(n) corresponds to the amount of transmit PSDneeded to achieve a target signal-to-noise ratio (SNR) or erasure ratefor a designated transmission. The transmission can be provided by afixed channel such as, for example, a channel quality feedback channelor a request channel. If a reference power level is capable of achievingthe corresponding target SNR or erasure rate, then the received SNR forthe other channel may be estimated as follows:SNR_(dch)(n)=SNR_(target) +ΔP(n).  (2)

In one example, a data channel and a corresponding control channelutilized by entities in system 300 can have similar interferencestatistics. This can occur, for example, when control and data channelsfrom different sectors interfere with one another. In such a case, theinterference offset for the channels may be calculated at terminal 310.Alternatively, the interference offset between the control channels anddata channels can be broadcasted by one or more sectors 320 and/or 330.

In another example, a transmit PSD for a data channel can be set basedon factors such as, for example, an amount of inter-sector interferenceterminal 310 is potentially causing to other terminals in neighboringsectors (e.g., sectors 104), an amount of intra-sector interferenceterminal 310 is potentially causing to other terminals in the samesector, a maximum allowable transmit power level for terminal 310,and/or other factors. These factors are described in more detail infrawith reference to power control techniques illustrated by FIGS. 3A-C.

With reference to FIG. 3A, initial forward link communications fromsectors 320 and 330 to terminal 310 in system 300 and measurements madeat terminal 310 based on those communications for an interference-basedpower control algorithm are illustrated. In accordance with one aspect,terminal 310 can receive data and/or signaling from serving sector 320on the forward link. In one example, signaling received from servingsector 320 includes an indication of channel quality from terminal 310to serving sector 320 on the reverse link. Additionally and/oralternatively, terminal 310 can obtain forward link channel qualitybased on data, pilots, and/or other signaling sent by serving sector 320on the forward link.

In accordance with another aspect, dominant interference sector 330 cantransmit interference indicators and/or other signaling to terminal 310on the forward link via one or more antennas 334. Interferenceindicators transmitted by dominant interference sector 330 can includean indication of reverse link interference present at dominantinterference sector 330. Additionally and/or alternatively, terminal 310can obtain forward link channel quality relative to dominantinterference sector 330 based on the indicators and/or other signalingreceived therefrom. Based on channel quality and/or interferenceinformation received by terminal 310, a difference in channel qualitybetween serving sector 320 and dominant interference sector 330 can thenbe determined by terminal 310 and utilized for further power controlcomputation.

In another example, channel quality information obtained by terminal 310from serving sector 320 and/or dominant interference sector 330 caninclude path loss information from an access point corresponding to thecoverage area of the access point. Path loss information can be derivedfrom forward link pilot measurement at terminal 310, reverse link pathloss feedback from an access point, and/or other appropriate sources.For example, a forward link pilot quality indicator channel (PQICH) froman access point can be used by terminal 310 as a source of path lossinformation.

Terminal 310 can utilize the information received from serving sector320 and/or dominant interference sector 330 to determine the amount ofinter-sector interference terminal 310 is potentially causing in variousmanners. In one example, the amount of inter-sector interference causedby terminal 310 can be directly estimated dominant interference sector330 and/or other neighbor access points (e.g., neighbor sectors 230) insystem 300. These directly estimated values can then be sent to terminal310 in order to allow terminal 310 to adjust its transmit poweraccordingly.

Alternatively, the amount of inter-sector interference caused byterminal 310 can be roughly estimated based on the total interferenceobserved by dominant interference sector 320 and/or neighbor accesspoints; channel gains for serving sector 320, dominant interferencesector 330, and/or neighbor access points; and a transmit power levelused by terminal 310. In one example, access points in system 300 canestimate a total or average currently observed amount of interferenceobserved by the access point. The access points can then broadcast theseinterference measurements for use by terminals in other sectors. By wayof non-limiting example, a single other-sector interference (OSI) bitcan be used by each access point to provide interference information.Accordingly, each access point may set its OSI bit (OSIB) as follows:

$\begin{matrix}{{O\; S\; I\;{B(N)}} = \{ \begin{matrix}{^{\prime}{1^{\prime},{{{if}\mspace{14mu} I\; O\;{T_{{meas},m}(n)}} \geq {I\; O\; T_{target}}},{and}}} \\{^{\prime}{0^{\prime},{{{if}\mspace{14mu} I\; O\;{T_{{meas},m}(n)}} < {I\; O\; T_{target}}},}}\end{matrix} } & (3)\end{matrix}$where IOT_(meas,m)(n) is the measured interference-over-thermal (IOT)value for an m-th sector at a time interval n and IOT_(target) is adesired operating point for the sector. As used in Equation (3), IOTrefers to a ratio of the total interference power observed by an accesspoint to thermal noise power. Based on this, a specific operating pointmay be selected for the system and denoted as IOT_(target). In oneexample, OSI can be quantized into multiple levels and accordinglycomprise multiple bits. For example, an OSI indication can have twolevels, such as IOT_(MIN) and IOT_(MAX), such that if an observed IOT isbetween IOT_(MIN) and IOT_(MAX) no adjustment to transmit power at aterminal 310 is to be made and if the observed IOT is above or below thegiven levels transmit power should be accordingly adjusted upward ordownward.

In accordance with one aspect, terminal 310 can estimate channel gain orpropagation path gain for access points that may receive reverse linktransmission from the terminal The channel gain for each of the accesspoints can be estimated by processing a pilot received from the accesspoints on the forward link. In one example, a channel gain ratio betweenserving sector 320 and a neighbor access point such as dominantinterference sector 330 can be utilized as a “relative distance”indicative of a distance to dominant interference sector 330 relative toa distance to serving sector 320. It can be observed that a channel gainratio for a neighbor access point will generally decrease as terminal310 moves toward a sector edge corresponding to serving sector 320 andgenerally increase as terminal 310 moves closer to serving sector 320.

Once terminal 310 obtains channel quality and/or interferenceinformation as illustrated by FIG. 3A, terminal 310 can calculate amaximum allowable transmit power based on interference experienced byvarious entities in system 300 and communicate this value back toserving sector 320 as illustrated in FIG. 3B. In one example, terminal310 can include a headroom computation component 318 for computing amaximum allowable transmit power value based on PA headroom of terminal310 and/or interference terminal 310 is causing at access points insystem 300. In one specific, non-limiting example, headroom computationcomponent 318 can utilize a difference in channel quality obtained fromserving sector 320 and dominant interference sector 330 as illustratedby FIG. 3A and a target interference level that terminal 310 can causeat a neighboring sector to determine an interference-based maximumallowable transmit power. While headroom computation component 318 isillustrated in FIG. 3B as a component of terminal 310, it should beappreciated that serving sector 320 and/or another suitable networkentity can also perform some or all of the calculations performed byheadroom computation component 318 either independently of or incooperation with terminal 310. The target interference level utilized byheadroom computation component 318 can be, for example, a predeterminedrise over the thermal noise power of system 300 (e.g., a predetermineddB rise), a predetermined rise over an interference level observed at asector, or a multiple of system thermal noise power. Further, the targetinterference level can be pre-configured or dynamically set by terminal310, serving sector 320, and/or another entity in system 300. In anotherexample, calculations performed by headroom computation component 318can be dynamic based on loading of serving sector 320, the observedchannel quality difference between serving sector 320 and dominantinterference sector 330, interference information received from servingsector 320, dominant interference sector 330, and/or other access pointsin system 300, types of content to be transmitted between serving sector320 and terminal 310 (e.g., voice, video, messaging data, etc.) and thesensitivity of such types of content to interference, and/or otherfactors.

In accordance with one aspect, headroom computation component 318 canmonitor OSI bits broadcast by neighbor access points in system 300 andcan be configured to only respond to an OSI bit of a dominantinterference sector 330, which can have the smallest channel gain ratioof the neighbor access points. In one example, if the OSI bit ofdominant interference sector 330 is set to ‘1,’ due to, for example, theaccess point observing higher than nominal inter-sector interference,then headroom computation component 318 can accordingly adjust themaximum allowable transmit power of terminal 310 downward. Conversely,if the OSI bit of dominant interference sector 330 is set to ‘0,’headroom computation component 318 can adjust the maximum allowabletransmit power of terminal 310 upward. Thus, an OSI bit from dominantinterference sector 330 can determine the direction in which headroomcomputation component 318 adjusts the transmit power of terminal 310.Headroom computation component 318 can then determine a magnitude oftransmit power adjustment for terminal 310 based on a current transmitpower level and/or transmit power delta for terminal 310, the channelgain ratio for dominant interference sector 330, and/or other factors.Alternatively, headroom computation component 318 can utilize OSI bitsfrom more than one access point and can utilize various algorithms toadjust the maximum allowable transmit power of terminal 310 based on themultiple received OSI bits.

In accordance with another aspect, data channels utilized by each sectorin system 300 can be multiplexed such that they are orthogonal to oneanother. However, despite such multiplexing, some loss in orthogonalitycan result from inter-carrier interference (ICI), inter-symbolinterference (ISI), and/or other causes, from which intra-sectorinterference can result. To mitigate intra-sector interference, thetransmit PSD of terminal 310 may be controlled by headroom computationcomponent 318 such that the amount of intra-sector interference thatterminal 310 may cause to other terminals in the same sector ismaintained within an acceptable level. This may be achieved, forexample, by constraining the transmit PSD delta, ΔP(n) , to be within acorresponding range ΔP(n)ε[ΔP_(min), ΔP_(max)], where ΔP_(min) andΔP_(max) are respectively the minimum and maximum transmit PSD deltasallowable for a given data channel.

In accordance with another aspect, terminal 310 can include a headroomfeedback component 312, which can send a transmit PSD delta computed byheadroom computation component 318 and a maximum number of subbands thatterminal 310 can support at the current transmit PSD delta,N_(sb,max)(n), to serving sector 320. In addition, desired quality ofservice (QoS) and buffer size parameters can also be transmitted toserving sector 320 by headroom feedback component 312. To reduce theamount of required signaling, headroom feedback component 312 cantransmit ΔP(n) and N_(sb,max)(n) at a subset of update intervals viain-band signaling on a data channel and/or by other means. It should beappreciated that a low transmit PSD delta corresponding to terminal 310does not mean that terminal 310 is not using all of the resourcesavailable to it. Instead, terminal 310 can be given more subbands fortransmission in order to use all its available transmit power.

In one example, PA headroom can be computed by headroom computationcomponent 318 as a ratio of total power available at terminal 310 topilot transmit power. Alternatively, headroom computation component 318can compute PA headroom as a maximum bandwidth parameter, which can beset by overhead parameters received from serving sector 320corresponding to a nominal transmit PSD. In such an example, headroominformation can be incorporated into maximum bandwidth feedback providedto serving sector 320 by headroom feedback component 312, which can becomputed by headroom computation component 318 as a ratio of total powerto a delta setting obtained from a delta-based power control algorithm.In addition, similar information can be incorporated into PSDconstraints or relative channel/interference feedback utilized byterminal 310 and serving sector 320. For example, a delta setting in adelta-based power control algorithm utilized by system 300 can bemodified to reflect a maximum per-user interference target.

Headroom feedback component 312 can provide PA headroom feedbackcombined with interference information to serving sector 320 in avariety of ways. For example, such information can be provided toserving sector 320 via a medium access control (MAC) header of a packet,such as a control channel packet; in a separate physical channel, suchas a channel for interference or power control feedback; as part ofchannel state information feedback (e.g., as one or more bits of thechannel state information); and/or by other suitable means.

Based on the feedback provided to serving sector 320 by terminal 310 asillustrated by FIG. 3B, serving sector 320 can then generate a transmitpower assignment for terminal 310 and communicate this assignment toterminal 310 as illustrated in FIG. 3C. In one example, a transmit powerfor terminal 310 can be assigned by a power control component 322 atserving sector 320. Power control component 322 can receive PA headroomfeedback, interference-based parameters such as an interference-basedmaximum allowable transmit power, and/or other parameters from terminal310 as illustrated in FIG. 3B for use in generating a transmit powerassignment for terminal 310. Parameters utilized by power controlcomponent 322 can be received together as a common communication or inseparate communications.

In accordance with one aspect, power control component 322 can determinea transmit power to be used by terminal 310 for communication withserving sector 320. Further, in one example, power control component 322can selectively determine whether or not to honor interference-basedparameters received from terminal 310 in determining its transmit powerassignment. For example, power control component 322 can analyze trafficquality of service (QoS) and/or other parameters and determine whether atransmit power that is higher than an interference-based maximumtransmit power provided by terminal 310, up to the transmit powercapability of terminal 310 as provided by its PA headroom feedback,should be assigned to terminal 310. Power control component 322 can thenassign a higher transmit power to terminal 310 accordingly. Once atransmit power assignment is determined by power control component 322,the assignment can be communicated back to terminal 310, whereuponterminal 310 can adjust its transmit power accordingly via a poweradjustment component 314.

In one specific example, power control component 322 can calculate ΔP(n)and/or other parameters utilized for generating a transmit powerassignment for terminal 310 based upon a reference PSD level P_(ref)(n),the power of signals received on reverse link channel quality indicatorand/or request channels from terminal 310, and/or other factors. In suchan example, carrier-to-interference offset can be determined along witha value for (IOT−RoT). These values can then be used to offset the powerof the signals reverse link channel quality indicator and/or requestchannels from terminal 310 and transmitted as power control commandsback to terminal 310.

In another example, total interference power received over the bandwidthof system 300 can be used by power control component 322 as aninterference control metric. The total interference power can be used todetermine a maximum per user interference target, which can then be usedto schedule terminal 310 for RL transmission in terms of bandwidth,timing, and/or other parameters. The per user interference target can beset, for example, to be a small fraction of total interference power forsystems with interference vulnerable deployment. By way of non-limitingexample, such a target can be utilized in a micro cell deployment sincean individual terminal on a cell edge in such a deployment may haveenough power to overwhelm a cell over a bandwidth of 5 or 10 MHz. Inaddition, such a target can be utilized in connection with cells usedfor communicating traffic having a significantly low latency that issusceptible to large IoT variations.

Referring to FIGS. 4-7, methodologies for power and interference controlin a wireless communication system are illustrated. While, for purposesof simplicity of explanation, the methodologies are shown and describedas a series of acts, it is to be understood and appreciated that themethodologies are not limited by the order of acts, as some acts may, inaccordance with one or more embodiments, occur in different ordersand/or concurrently with other acts from that shown and describedherein. For example, those skilled in the art will understand andappreciate that a methodology could alternatively be represented as aseries of interrelated states or events, such as in a state diagram.Moreover, not all illustrated acts may be required to implement amethodology in accordance with one or more embodiments.

With reference to FIG. 4, illustrated is a methodology 400 for providingreverse link feedback for power control and interference management in awireless communication system (e.g., system 300). It is to beappreciated that methodology 400 can be performed by, for example, aterminal (e.g., terminal 310) and/or any other appropriate networkentity. Methodology 400 begins at block 402, wherein a combined

PA headroom and interference value for communication with an accesspoint (e.g., serving sector 320) is determined

In accordance with one aspect, the PA headroom portion of the valuedetermined at block 402 can be computed as headroom with respect to apilot channel on which the entity performing methodology 400 istransmitting, a maximum available bandwidth based on a nominal PSDvalue, a maximum PSD achievable by the entity performing methodology400, and/or other appropriate parameters. The PA headroom portion of thevalue determined at block 402 can then be combined with aninterference-based power value, which can be determined based on channelquality and/or interference information received from a serving accesspoint (e.g., serving sector 320) and/or neighbor access points (e.g.,dominant interference sector 330 and/or other neighbor access points) inthe system. In one example, the interference-based power value can bedetermined at block 402 based on forward link path loss informationobtained from pilots and/or other information received from the servingaccess point and/or neighbor access points. Alternatively, the value canbe computed based on reverse link path loss and/or channel qualityfeedback from the access points. In another example, theinterference-based power value can also be determined at block 402 basedon OSI information obtained from neighbor access points. For example,the power can be adjusted upward if indications of high interference arereceived or downward if indications of lower interference are received.

Upon completing the act described at block 402, methodology 400continues to block 404, wherein the combined value determined at block402 is transmitted to the access point. Transmission at block 404 can beaccomplished in a variety of ways. For example, the combined valuedetermined at block 402 can be transmitted to the access point in a MACheader of a packet and can be transmitted on a dedicated channel and/orcombined with channel state information feedback. Further, the combinedvalue determined at block 402 can be transmitted to the access pointtogether with, separately from, or in place of PA headroom feedback thatdoes not depend on interference observed in the system.

FIG. 5 illustrates a methodology 500 for conducting reverse link powercontrol in a wireless communication system. It is to be appreciated thatmethodology 500 can be performed by, for example, an access point (e.g.,serving sector 320) and/or any other suitable network entity.Methodology 500 begins at block 502, wherein a combined PA headroom andinterference value is received from an access terminal (e.g., terminal310). In one example, the combined value received at block 502 cancorrespond to a maximum power level at which the access terminal cantransmit while keeping interference caused by the access terminal withinacceptable levels. Additionally and/or alternatively, the combined valuereceived at block 502 can correspond to a maximum bandwidth the accessterminal can support while causing an acceptable amount of interferenceat neighboring access points. In another example, the combined value canbe received with, separate from, or in place of a PA headroom parameterfrom the access terminal that does not take interference into account.

Methodology 500 can then proceed to block 504, wherein a transmit powerfor the access terminal is assigned based on the combined value receivedat block 502. In one example, a transmit power can be assigned for theaccess terminal at block 504 such that the maximum transmit power and/orcorresponding bandwidth parameter received at block 502 from the accessterminal will not be exceeded. Alternatively, if a PA headroom parameterthat is not based on interference is also received at block 502, qualityof service and/or other parameters can be analyzed at block 504. Basedon this analysis, a determination can be made at block 504 as to whetherto honor or discard the combined value received at block 502 and insteaduse the non-interference-based PA headroom parameter as a maximumtransmit power that can be assigned to the access terminal

FIG. 6 illustrates a methodology 600 for generating and transmittingreverse link feedback for power control and interference management in awireless communication system. It is to be appreciated that methodology600 can be performed by, for example, a terminal and/or any otherappropriate network entity in a wireless communication system.Methodology 600 begins at blocks 602, wherein channel quality and/orinterference parameters are obtained from a serving sector and adominant interference sector. In one example, channel quality and/orinterference parameters can be obtained at block 602 for the forwardlink by analyzing pilots and/or other information received from theserving sector and dominant interference sector on the forward link.Additionally and/or alternatively, channel quality and/or interferenceparameters obtained at block 602 can include reverse link channelquality and interference feedback transmitted by the sectors. Next, atblock 604, a target interference level is determined. The targetinterference level determined at block 604 can be, for example, apredetermined rise over thermal noise power, a predetermined rise overan interference level observed at a sector, a multiple of system thermalnoise power, and/or another appropriate target. Further, the targetinterference level can be dynamically determined at block 604 based onchanges in network conditions, a type of data to be communicated, and/orother factors.

Based on the information obtained at block 602 and the targetinterference level determined at block 604, a maximum allowable transmitpower can then be computed at block 606. In one example, the maximumallowable transmit power computed at 606 can be computed by determininga maximum transmit power and/or corresponding bandwidth that constrainsthe amount of interference caused by an entity performing methodology600 at neighboring sectors within an allowable range. Once theinterference-based maximum allowable transmit power is computed at block606, methodology 600 can then conclude at block 608, wherein theinterference-based transmit power is transmitted to the serving sectorwith PA headroom feedback. Similar to the transmission performed atblock 404 of methodology 400, the interference-based transmit powercomputed at block 606 can be transmitted to the serving sector in a MACheader of a packet and can be transmitted on a dedicated channel and/orcombined with channel state information feedback. Further, theinterference-based transmit power can be combined with the PA headroomfeedback prior to transmission at block 608, or alternatively theinterference-based transmit power and PA headroom feedback can betransmitted as separate parameters.

FIG. 7 illustrates a methodology 700 for assigning a transmit power to aterminal for reverse link power control and interference management in awireless communication system. It is to be appreciated that methodology700 can be performed by, for example, an access point and/or any othersuitable network entity in a wireless communication system. Methodology700 begins at block 702, wherein PA headroom feedback and aninterference-based maximum allowable transmit power are received from aterminal The PA headroom feedback and interference-based value can bereceived at block 702 together or as separate parameters. Further, theparameters can be received at block 702 in a MAC header of a packet, andthey can be further received on a dedicated channel and/or combined withchannel state information feedback from the terminal.

Upon receiving the PA headroom feedback and interference-based value atblock 702, methodology 700 can proceed to block 704, wherein adetermination is made as to whether to honor the interference-basedvalue. In one example, the PA headroom feedback received at block 702can correspond to a maximum transmit power that the terminal is capableof utilizing while the interference-based value can correspond to amaximum transmit power that can be utilized by the terminal whilekeeping interference caused by the terminal within a target interferencelevel. Accordingly, the determination made at block 704 can includeanalyzing quality of service parameters for the terminal and/or othersuitable parameters to determine whether it is more beneficial torequire the terminal to transmit at a higher power than that provided bythe interference-based value despite the interference that doing so maycause within the system.

If it is determined that the interference-based value is to be honoredat block 704, methodology 700 proceeds to block 706, wherein a transmitpower is assigned for the terminal based on the PA headroom feedback andthe interference-based value. Alternatively, if it is determined thatthe interference-based value is to be discarded at block 704,methodology 700 instead proceeds to block 708, wherein a transmit poweris assigned for the terminal based on the PA headroom feedback alone. Inboth cases, methodology 700 then concludes at block 710, wherein thetransmit power assigned at block 706 or block 708 is communicated to theterminal, which can then adjust its transmit power accordingly.

Referring now to FIG. 8, a block diagram illustrating an examplewireless communication system 800 in which one or more embodimentsdescribed herein may function is provided. In one example, system 800 isa multiple-input multiple-output (MIMO) system that includes atransmitter system 810 and a receiver system 850. It should beappreciated, however, that transmitter system 810 and/or receiver system850 could also be applied to a multi-input single-output system wherein,for example, multiple transmit antennas (e.g., on a base station), maytransmit one or more symbol streams to a single antenna device (e.g., amobile station). Additionally, it should be appreciated that aspects oftransmitter system 810 and/or receiver system 850 described herein couldbe utilized in connection with a single output to single input antennasystem.

In accordance with one aspect, traffic data for a number of data streamsare provided at transmitter system 810 from a data source 812 to atransmit (TX) data processor 814. In one example, each data stream canthen be transmitted via a respective transmit antenna 824. Additionally,TX data processor 814 can format, code, and interleave traffic data foreach data stream based on a particular coding scheme selected for eachrespective data stream in order to provide coded data. In one example,the coded data for each data stream may then be multiplexed with pilotdata using OFDM techniques. The pilot data can be, for example, a knowndata pattern that is processed in a known manner. Further, the pilotdata may be used at receiver system 850 to estimate channel response.Back at transmitter system 810, the multiplexed pilot and coded data foreach data stream can be modulated (i.e., symbol mapped) based on aparticular modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM)selected for each respective data stream in order to provide modulationsymbols. In one example, data rate, coding, and modulation for each datastream may be determined by instructions performed on and/or provided byprocessor 830.

Next, modulation symbols for all data streams can be provided to a TXprocessor 820, which may further process the modulation symbols (e.g.,for OFDM). TX MIMO processor 820 may then provides N_(T) modulationsymbol streams to N_(T) transmitters (TMTR) 822 a through 822 t. In oneexample, each transmitter 822 can receive and process a respectivesymbol stream to provide one or more analog signals. Each transmitter822 may then further condition (e.g., amplify, filter, and upconvert)the analog signals to provide a modulated signal suitable fortransmission over a MIMO channel. Accordingly, N_(T) modulated signalsfrom transmitters 822 a through 822 t can then be transmitted from N_(T)antennas 824 a through 824 t, respectively.

In accordance with another aspect, the transmitted modulated signals canbe received at receiver system 850 by N_(R) antennas 852 a through 852r. The received signal from each antenna 852 can then be provided to arespective receiver (RCVR) 854. In one example, each receiver 854 cancondition (e.g., filter, amplify, and downconvert) a respective receivedsignal, digitize the conditioned signal to provide samples, and thenprocesses the samples to provide a corresponding “received” symbolstream. An RX MIMO/data processor 860 can then receive and process theN_(R) received symbol streams from N_(R) receivers 854 based on aparticular receiver processing technique to provide N_(T) “detected”symbol streams. In one example, each detected symbol stream can includesymbols that are estimates of the modulation symbols transmitted for thecorresponding data stream. RX processor 860 can then process each symbolstream at least in part by demodulating, deinterleaving, and decodingeach detected symbol stream to recover traffic data for a correspondingdata stream. Thus, the processing by RX data processor 818 may becomplementary to that performed by TX MIMO processor 820 and TX dataprocessor 814 at transmitter system 810.

In accordance with one aspect, the channel response estimate generatedby RX processor 860 may be used to perform space/time processing at thereceiver, adjust power levels, change modulation rates or schemes,and/or other appropriate actions. Additionally, RX processor 860 mayfurther estimate channel characteristics such as, for example,signal-to-noise-and-interference ratios (SNRs) of the detected symbolstreams. RX processor 860 can then provide estimated channelcharacteristics to a processor 870. In one example, RX processor 860and/or processor 870 can further derive an estimate of the “operating”SNR for the system. Processor 870 can then provide channel stateinformation (CSI), which may comprise information regarding thecommunication link and/or the received data stream. This information mayinclude, for example, the operating SNR. The CSI can then be processedby a TX data processor 878, modulated by a modulator 880, conditioned bytransmitters 854 a through 854 r, and transmitted back to transmittersystem 810.

Back at transmitter system 810, the modulated signals from receiversystem 850 can then be received by antennas 824, conditioned byreceivers 822, demodulated by a demodulator 840, and processed by a RXdata processor 842 to recover the CSI reported by receiver system 850.In one example, the reported CSI can then be provided to processor 830and used to determine data rates as well as coding and modulationschemes to be used for one or more data streams. The determined codingand modulation schemes can then be provided to transmitters 822 forquantization and/or use in later transmissions to receiver system 850.Additionally and/or alternatively, the reported CSI can be used byprocessor 830 to generate various controls for TX data processor 814 andTX MIMO processor 820.

In one example, processor 830 at transmitter system 810 and processor870 at receiver system 850 direct operation at their respective systems.Additionally, memory 832 at transmitter system 810 and memory 872 atreceiver system 850 can provide storage for program codes and data usedby processors 830 and 870, respectively. Further, at receiver system850, various processing techniques may be used to process the N_(R)received signals to detect the N_(T) transmitted symbol streams. Thesereceiver processing techniques can include spatial and space-timereceiver processing techniques, which may also be referred to asequalization techniques, and/or “successive nulling/equalization andinterference cancellation” receiver processing techniques, which mayalso be referred to as “successive interference cancellation” or“successive cancellation” receiver processing techniques.

FIG. 9 is a block diagram of a system 900 that provides reverse linkfeedback for interference control in a wireless communication system inaccordance with various aspects described herein. In one example, system900 includes an access terminal 902. As illustrated, access terminal 902can receive signal(s) from one or more access points 904 and transmit tothe one or more access points 904 via an antenna 908. Additionally,access terminal 902 can comprise a receiver 910 that receivesinformation from antenna 908. In one example, receiver 910 can beoperatively associated with a demodulator (Demod) 912 that demodulatesreceived information. Demodulated symbols can then be analyzed by aprocessor 914. Processor 914 can be coupled to memory 916, which canstore data and/or program codes related to access terminal 902.Additionally, access terminal 902 can employ processor 914 to performmethodologies 400, 600, and/or other appropriate methodologies. Accessterminal 902 can also include a modulator 918 that can multiplex asignal for transmission by a transmitter 920 via antenna 908 to one ormore access points 904.

FIG. 10 is a block diagram of a system 1000 that coordinates reverselink power control and interference management in a wirelesscommunication system in accordance with various aspects describedherein. In one example, system 1000 includes a base station or accesspoint 1002. As illustrated, access point 1002 can receive signal(s) fromone or more access terminals 1004 via a receive (Rx) antenna 1006 andtransmit to the one or more access terminals 1004 via a transmit (Tx)antenna 1008.

Additionally, access point 1002 can comprise a receiver 1010 thatreceives information from receive antenna 1006. In one example, thereceiver 1010 can be operatively associated with a demodulator (Demod)1012 that demodulates received information. Demodulated symbols can thenbe analyzed by a processor 1014. Processor 1014 can be coupled to memory1016, which can store information related to code clusters, accessterminal assignments, lookup tables related thereto, unique scramblingsequences, and/or other suitable types of information. In one example,access point 1002 can employ processor 1014 to perform methodologies500, 700, and/or other appropriate methodologies. Access point 1002 canalso include a modulator 1018 that can multiplex a signal fortransmission by a transmitter 1020 through transmit antenna 1008 to oneor more access terminals 1004.

FIG. 11 illustrates an apparatus 1100 that facilitates reverse linkfeedback for interference management in a wireless communication system(e.g., system 300). It is to be appreciated that apparatus 1100 isrepresented as including functional blocks, which can be functionalblocks that represent functions implemented by a processor, software, orcombination thereof (e.g., firmware). Apparatus 1100 can be implementedin a terminal (e.g., terminal 310) and/or another suitable networkentity and can include a module for determining a combined PA headroomand interference value 1102. Further, apparatus 1100 can include amodule for transmitting the combined value to an access point 1104.

FIG. 12 illustrates an apparatus 1200 that facilitates the generationand transmission of reverse link feedback for power control andinterference management in a wireless communication system. It is to beappreciated that apparatus 1200 is represented as including functionalblocks, which can be functional blocks that represent functionsimplemented by a processor, software, or combination thereof (e.g.,firmware). Apparatus 1200 can be implemented in a terminal and/oranother suitable network entity and can include a module for obtainingchannel quality and interference parameters from a serving sector and/orother sectors 1202. Further, apparatus 1200 can include a module fordetermining a target interference level 1204, a module for computing amaximum transmit power from the channel quality and interferenceparameters and the target interference level 1206, and a module fortransmitting the maximum transmit power and PA headroom feedback to theserving sector 1206.

FIG. 13 illustrates an apparatus 1300 that facilitates reverse linkpower control in a wireless communication system. It is to beappreciated that apparatus 1300 is represented as including functionalblocks, which can be functional blocks that represent functionsimplemented by a processor, software, or combination thereof (e.g.,firmware). Apparatus 1300 can be implemented in an access point (e.g.,serving sector 320) and/or another suitable network entity in a wirelesscommunication system and can include a module for receiving a combinedPA headroom and interference value from an access terminal 1302.Further, apparatus 1300 can include a module for generating a transmitpower assignment based on the combined value 1304.

FIG. 14 illustrates an apparatus 1400 that facilitates the provision ofa transmit power assignment to a terminal for reverse link power controland interference management in a wireless communication system. It is tobe appreciated that apparatus 1400 is represented as includingfunctional blocks, which can be functional blocks that representfunctions implemented by a processor, software, or combination thereof(e.g., firmware). Apparatus 1400 can be implemented in an access pointand/or another suitable network entity in a wireless communicationsystem and can include a module for receiving PA headroom feedback andan interference-based maximum transmit power from a terminal 1402.Further, apparatus 1400 can include a module for assigning a transmitpower for the terminal based on the PA headroom feedback and/or theinterference-based maximum transmit power 1404 and a module forcommunicating the assigned transmit power to the terminal 1406.

It is to be understood that the embodiments described herein may beimplemented by hardware, software, firmware, middleware, microcode, orany combination thereof When the systems and/or methods are implementedin software, firmware, middleware or microcode, program code or codesegments, they may be stored in a machine-readable medium, such as astorage component. A code segment may represent a procedure, a function,a subprogram, a program, a routine, a subroutine, a module, a softwarepackage, a class, or any combination of instructions, data structures,or program statements. A code segment may be coupled to another codesegment or a hardware circuit by passing and/or receiving information,data, arguments, parameters, or memory contents. Information, arguments,parameters, data, etc. may be passed, forwarded, or transmitted usingany suitable means including memory sharing, message passing, tokenpassing, network transmission, etc.

For a software implementation, the techniques described herein may beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. The software codes may be storedin memory units and executed by processors. The memory unit may beimplemented within the processor or external to the processor, in whichcase it can be communicatively coupled to the processor via variousmeans as is known in the art.

What has been described above includes examples of one or moreembodiments. It is, of course, not possible to describe everyconceivable combination of components or methodologies for purposes ofdescribing the aforementioned embodiments, but one of ordinary skill inthe art may recognize that many further combinations and permutations ofvarious embodiments are possible. Accordingly, the described embodimentsare intended to embrace all such alterations, modifications andvariations that fall within the spirit and scope of the appended claims.Furthermore, to the extent that the term “includes” is used in eitherthe detailed description or the claims, such term is intended to beinclusive in a manner similar to the term “comprising” as “comprising”is interpreted when employed as a transitional word in a claim.Furthermore, the term “or” as used in either the detailed description orthe claims is meant to be a “non-exclusive or.”

What is claimed is:
 1. A method for providing feedback for power controlin a wireless communication system, comprising: determining a combinedpower amplifier (PA) headroom and interference value for communicationwith an access point, wherein the combined PA headroom and interferencevalue comprises a value based on a combination of a PA headroom portionof the value and an interference portion of the value; and transmittingthe combined value to the access point.
 2. The method of claim 1,wherein the transmitting includes transmitting the combined value in amedium access control (MAC) header of a packet.
 3. The method of claim1, wherein the transmitting includes transmitting the combined value ina dedicated channel.
 4. The method of claim 1, wherein the transmittingincludes transmitting the combined value as part of channel stateinformation feedback.
 5. The method of claim 1, wherein the determiningincludes: obtaining one or more of interference information and channelquality information from the access point and one or more neighboraccess points; and determining the combined value based at least in parton the obtained information.
 6. The method of claim 5, wherein theobtaining includes obtaining forward link channel quality informationfrom pilots transmitted by at least one of the access point and the oneor more neighbor access points.
 7. The method of claim 5, wherein theobtaining includes obtaining reverse link channel quality informationbased on feedback transmitted by at least one of the access point andthe one or more neighbor access points.
 8. The method of claim 1,wherein the determining a combined PA headroom and interference valueincludes determining the combined value based at least in part on atarget increase in interference experienced by at least one of theaccess point and a neighbor access point.
 9. The method of claim 8,wherein the determining the PA headroom portion of the combined PAheadroom and interference value includes determining a maximumsupportable transmit power spectral density (PSD) based on the targetincrease in interference.
 10. The method of claim 8, wherein thedetermining the PA headroom portion of the combined PA headroom andinterference value includes determining a maximum supportable bandwidthbased on the target increase in interference and a reference transmitPSD.
 11. The method of claim 1, wherein the transmitting includestransmitting the combined value and an interference-independent PAheadroom value to the access point.
 12. The method of claim 1, furthercomprising: receiving an assignment for one or more of a transmit powerand a bandwidth from the access point; and adjusting a transmit power ora bandwidth used for communication with the access point based on theassignment.
 13. A non-transitory computer-readable medium havinginstructions stored thereon that, when executed, cause one or moreprocessors to: determine a power amplifier (PA) headroom parameter andan interference-based headroom parameter, wherein the combined PAheadroom and interference value comprises a value based on a combinationof a PA headroom portion of the value and an interference portion of thevalue; and communicate the PA headroom parameter and theinterference-based headroom parameter to an access point.
 14. Thenon-transitory computer-readable medium of claim 13, wherein tocommunicate the PA headroom parameter and the interference-basedheadroom parameter, the instructions cause the one or more processors tocommunicate the PA headroom parameter and the interference-basedheadroom parameter in a common transmission.
 15. The non-transitorycomputer-readable medium of claim 13, wherein to communicate the PAheadroom parameter and the interference-based headroom parameter, theinstructions cause the one or more processors to communicate the PAheadroom parameter and the interference-based headroom parameter inseparate transmissions.
 16. The non-transitory computer-readable mediumof claim 13, wherein to communicate the PA headroom parameter and theinterference-based headroom parameter, the instructions cause the one ormore processors to communicate the interference-based headroom parameterin a MAC header of a packet.
 17. The non-transitory computer-readablemedium of claim 13, wherein to communicate the PA headroom parameter andthe interference-based headroom parameter, the instructions cause theone or more processors to communicate the interference-based headroomparameter in a dedicated channel.
 18. The non-transitorycomputer-readable medium of claim 13, wherein to communicate the PAheadroom parameter and the interference-based headroom parameter, theinstructions cause the one or more processors to communicate theinterference-based headroom parameter as part of channel stateinformation feedback.
 19. The non-transitory computer-readable medium ofclaim 13, further comprising instructions that cause the one or moreprocessors to: receive one or more of a transmit power and a bandwidthto be used for communication with the access point; and communicate withthe access point using one or more of the transmit power and thebandwidth received for use.
 20. An integrated circuit that executescomputer-executable instructions for interference control in a wirelesscommunication system, the instructions comprising: obtaining a maximumper-user interference and a path loss to at least one sector in thewireless communication system; computing a combined power amplifier (PA)headroom and interference value based at least in part on the maximumper-user interference and the path loss, wherein the combined PAheadroom and interference value comprises a value based on a combinationof a PA headroom portion of the value and an interference portion of thevalue; and transmitting the combined value to a serving sector.
 21. Theintegrated circuit of claim 20, wherein the instructions for obtaining amaximum per-user interference and a path loss include obtaining the pathloss based at least in part on forward link pilots received from atleast one sector in the wireless communication system.
 22. Theintegrated circuit of claim 20, wherein the instructions for obtaining amaximum per-user interference and a path loss include obtaining the pathloss based at least in part on reverse link path loss feedback receivedfrom at least one sector in the wireless communication system.
 23. Theintegrated circuit of claim 20, wherein the instructions fortransmitting include transmitting the combined value and aninterference-independent PA headroom value to the serving sector.